Millennium Cohort Study

The Millennium Cohort Study (MCS), known as ‘Child of the New Century’ to cohort members and their families, is following the lives of around 19,000 young people born across England, Scotland, Wales and Northern Ireland in 2000-01. The study began with an original sample of 18,818 cohort members.

What’s in the study?

The MCS provides multiple measures of the cohort members’ physical, socio-emotional, cognitive and behavioural development over time, as well as detailed information on their daily life, behaviour and experiences. Alongside this, rich information on economic circumstances, parenting, relationships and family life is available from both resident parents.

National Pupil Database (NPD) records have also been linked to the MCS data, so far including attainment up to Key Stage 2, and updated linkage, up to GCSE (Key Stage 4) is underway.

What has the study found?

MCS has provided important evidence to show how circumstances in the very first stages of life can influence later health and development.

MCS sweeps

We have completed six MCS sweeps to date. The most recent sweep was when cohort members were 14 years old. We are currently surveying them again, at age 17. Click on a sweep below to learn more about the information collected.

5 February 2019
Professor Emla Fitzsimons appeared on BBC Radio 4’s Analysis programme last night (4 February) to highlight Millennium Cohort Study research looking at the impact of family structure on children’s prospects.

17 January 2019
Children who experience a family break-up in late childhood and early adolescence are more likely to have emotional and behavioural problems than those living with both parents, according to a new study.

Special features of this study

Sample design

Unlike the previous three national birth cohorts, which all share the same birth week, MCS cohort members were born over a 17 month period (September 2000-January 2002). This allows researchers to investigate season of birth effects in children’s outcomes and trajectories.

The population from which every child should have a known, non-zero chance of selection was defined as: all those:

born within eligible dates: between 1/9/2000 and 31/8/2001 (England & Wales), and between 23/11/2000 and 11/01/2002 (Scotland and Northern Ireland),

alive and living in the UK at age nine months and

eligible to receive Child Benefit at that age.

The sampling strategy was to make a selection of areas of residence, and within them to recruit 100 per cent of the children born in the eligible period. The statistical geography available for such clusters in 2000-01 was the boundaries of electoral wards as they stood before updating at the 2001 census.

Importantly, certain sub-groups of the population were intentionally over-sampled, namely children living in disadvantaged areas, children of ethnic minority backgrounds and children growing up in the smaller nations of the UK.

By the end of fieldwork for the Age 9-Months Sweep, 18,552 families had been interviewed, and the cohort included 18,818 children, allowing for 246 sets of twins and 10 sets of triplets. This represents a response rate of 72 per cent of all the families with eligible children living at nine months in the sampled wards.

The Age 3 Sweep in 2003-04 provided an opportunity to catch up with families who should have been in the Age 9-Months Sweep, but had been missed because they had only recently moved to an eligible address. This group of ‘new families’ was only recruited in England. The boost to the sample from the ‘new families’ brought the total of all families ever interviewed to 19,243 (and the number of children ever taking part up to 19,517).

There is no sample refreshment by immigrants. All the MCS children were resident in the UK at nine months, and would cease to be eligible if they leave the UK (but resume eligibility on return to the UK).

Biomedical data

Objective physical measurements have been taken since the age of 3. They include height, weight, waist measurement and body fat. At ages 7 and 14, activity monitors were worn in order to measure physical activity and sedentary behaviour.

At age 14, cohort members and their residential natural parents were asked to provide a saliva sample for DNA extraction and subsequent genotyping. This is the first time a triad of DNA samples has been collected from 2 biological parents and their child in a large scale nationally representative study.

Linked administrative data

Administrative data has been linked to the survey data collected in the study in the domains of health and education.

Linked health data is available from birth registration records and maternity records. Linked educational data from the National Pupil Database, comprising Key Stage 1 and Key Stage 2 assessment scores, is also available.

Cognitive assessments

The MCS has been carrying out cognitive assessments with cohort members since the age of three, using leading standardised age-appropriate assessments such as the British Ability Scales.

Assessments range from measuring preschool knowledge of numbers, letter, shapes and sizes through numeracy and vocabulary to non-verbal assessments of pattern construction and touch screen measures of spatial working memory and decision making. They provide objective measures of the cohort members’ numeric and linguistic abilities, and how they develop across childhood and adolescence.

Information from fathers

Data has been collected from resident fathers, including step-fathers, as well as from mothers at all sweeps. This was an innovation for a national cohort, and reflected strong scientific interest in the role of fathers and the increasing diversity of family life in the UK.

Principal Investigator

Emla FitzsimonsProfessor of Economics and Director of the Millennium Cohort Study

Emla is the Director of the UK Millennium Cohort Study, a longitudinal birth cohort study following children born at the turn of the new century. Her research is focused on the development of human capital throughout the life course, and in particular how experiences and circumstances in early life and childhood affect causally the acquisition of skills later on.

More related content

SEN, school life and future aspirations

14 June 2018

This briefing, based on data from the Millennium Cohort Study, explores how children with persistent SEN felt about school, their academic ability and their future educational and occupational aspirations at age 14…